Membrane tube formation by motor proteins: forces and dynamics

Abstract

Membrane tubes are ubiquitous within cells. They have a diameter of approximately 50 nanometers, and are formed when a sufficiently large localized force is exerted on a membrane. Important generators of this force are the motor proteins that can move along cytoskeletal filaments. We studied membrane tube formation by motor proteins from giant vesicles in an in vitro reconstituted system, and showed that motor proteins can dynamically associate to form clusters that work together. In addition, the physical parameters that determine the force required to form tubes were examined, and it was found that the force barrier for tube formation increases with the area the pulling force is exerted on. Finally, some first results are presented on the competition between motor proteins of opposite directionality. Our findings suggest regulatory mechanisms that may be used for the intracellular spatial organization of membranes.